This is a huge ancient forest world discovered 300 meters down a sinkhole in Hubei, China, containing a unique ecosystem of ancient trees, plants and animals.

The beautiful landscape is located in a region of karst topography, which is formed of soluble rocks such as limestone.

Its balanced ecosystem relies on natural weather events, such as floods, bringing in excess rainwater, which in turn washes leaves and plants into the cave.

Bats have also been found to need inside caves causing piles of droppings, known as guano, to accumulate. Bacteria in the cave can then decompose this and it acts as a form of compost for plants.

The area partially obscured by shadow that receives little light is known as the 'twilight zone'. It temperature is more constant than the entrance zone and is typically cooler, making it more suitable for fungi to grow.

The so-called 'dark zone' receives no light and a constant temperature and plants won't grow here. Instead it is home to troglobites - organisms that developed and adapted to live in such dark environments.

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